Bifocals, the
combination of both concave and convex lenses for both types of vision
correction, a top lens for distant viewing and a lower lens for reading, were
developed around 1760 by the American statesman and inventor Benjamin Franklin.

Franklin was
getting older and suffered from both myopia and presbyopia. Getting tired of
switching between two types of glasses, he devised a way to have both types of
lenses fit into the frame. The distance lens was placed at the top and the
up-close lens was placed at the bottom.

Historians
have from time to time produced evidence to suggest that others may have
preceded him in the invention; however, a correspondence between George Whatley
and John Fenno, editor of The Gazette of the United States, suggested that
Franklin had indeed invented bifocals, and perhaps 50 years earlier than had
been originally thought.